This thesis provides a comparative analysis of late-twelfth and early-thirteenth century Tristan verse narratives from the French- and German-speaking worlds, in order to gain a more nuanced picture of how these specific writers reflect contemporary debates on interpretation and fictionality in their own works. While there is a vast body of critical literature on these texts, and a large amount of this scholarship examines the way that interpretation functions in these works, critics have so far not adequately considered how the Tristan texts from this period as a body engage with contemporary medieval debates on the relationship between truth, lies and fiction, particularly in relation to fiction as a new category for vernacular literary culture. Therefore, this thesis analyses how literary practice during this period is reflected in these texts, particularly regarding truth, lies, interpretation and authority. The first part of the thesis thoroughly studies the use of verbal and visual signs in the texts, focusing on the way that characters both construct and interpret those signs. The second part of the thesis examines storytelling in these texts. This focuses firstly on the narrators’ interjections into their works, discussing for example their relationship to their sources. Secondly, this analyses how the characters within the texts tell stories to each other, particularly those relating to their own pasts. Together, these two parts argue that interpretation and authority are key concerns for the writers of these texts. In conclusion, this thesis proposes that the writers of the Tristan verse narratives are participating in a dialogue about literary practice, interpretation and authority as they attempt to engage with the new narrative mode of literary vernacular romance.